Example: you installed solar panels and are going to get a tax credit.


For the tax credit part, you could create special receipt(s) for the year(s) and amount(s).


If you are treating the cost of the solar panel as simply paid for out of discretionary spending, you'd enter the credit as a special receipt as described above and not enter any special expense. 


If you enter the cost of the solar panel as a special expense, you could net out the tax credit and capture it that way. You could also enter the full cost of the solar panel as a special expense and then represent the tax credits as special receipt. 


Use whichever approach seems most transparent to you.